U.S. Pat. No. 5,327,034, issued Jul. 5, 1994, discloses an electrically motorized wheel comprising a fixed shaft, having wheel on it, and a rotor in the form of an electric winding, which is located outside the stator on the wheel. The stator is coaxial with the rotor and is located on the fixed part of the structure with an inner side of the rotor.
The patent does not show a connection with the hydraulic braking system. Traditionally, passenger vehicles use a hydraulic braking system. A hydraulic braking system is reliable and safe. Electric vehicles should use it too, at least as a reserve system. There is a need for an additional conventional braking system for reliability and for braking during such driving modes, which expect that braking from recovery becomes inefficient.
U.S. Pat. No. 3,621,929, issued Sep. 24, 1969, discloses a brake system for electrically operated vehicles comprising a main cylinder, a hydraulic line connected to the main cylinder and a main cylinder actuation pedal, a battery, an electric motor capable of converting the battery's energy into kinetic energy of rotation of the vehicle's drive axis, a control means associated with the accelerator pedal and the power supply line to the motor, the position of the accelerator pedal and, if necessary, the activation of the electric current supply to the electric motor, and activation of generator mode of the electric motor during braking with ability of transformation of kinetic energy of motion into electrical energy and storing it in a battery, monitoring the braking torque means adapted to ensure engagement of the hydraulic system only when the braking torque has certain value.
This system provides an interrelation between the operation of the hydraulic braking system and the braking system by the electric generator with the transformation of the kinetic energy of the vehicle to electrical energy, preventing the activation of the hydraulic braking system in cases where braking with recuperation is possible. This allows saving the electric energy used for driving the vehicle and mechanical part of the hydraulic braking system.
However, the above mentioned system has a drawback associated with the peculiarity of connecting the phases of an induction AC motor. The preferred mode of power supply for starting the electric motor at the beginning of the vehicle's movement is characterized with the “star” connection of the windings, because the required starting torque is provided with a lower current load. For development of the maximum power during acceleration it is need to change windings to the “wye” connection. When the motor is connected to only one of the above circuits, the motor will either not be able to reach maximum power when windings have a “star” connection, or it will be overloaded with starting currents, and windings can burn out when the vehicle starts to move, when connected with a “triangle.” Switching from one circuit to another occurs instantly, not smoothly. It is like a gear shift in a manual gearbox. Therefore, not in all ranges of torque will be ensured the optimum feeding of the motor coils, which is the first drawback. The second drawback of such a switching from one circuit to another during driving is the a shock load causing damage of the mechanisms, as well as an excessive electrical load on the windings of the motor causing damage of the wires.
Many other systems associated with in-wheel electric motors with brakes have been disclosed. See, for example, U.S. Pat. Publication Nos. 2008/0078631, 2014/0015382 and 2017/028835, as well as U.S. Pat. Nos. 2,506,146, 3,584,276, 4,962,969, 5,442,250 and 5,573,312. None of them are germane to the present invention.